Boost Conversions with the Decoy Effect: Design Strategies and Real‑World Cases

Concept

The decoy effect (also called the asymmetrically dominated effect) occurs when a third option (the decoy) is introduced to increase the attractiveness of an existing option (the target). The remaining option(s) are competitors.

When the Decoy Effect Occurs

Two typical situations trigger the effect:

When a decision‑maker has a clear preference, adding a decoy can shift that preference. Dan Ariely’s experiment with Economist magazine subscriptions showed that adding a print version caused many users who originally chose the digital‑only option to switch to the combined digital + print package.

When a decision‑maker faces two or more options of roughly equal perceived value, a decoy can steer the choice. Trueblood’s 2015 car‑choice experiment demonstrated that adding a third car (higher fuel consumption, same price as the more efficient option) increased selection of the efficient car.

Decoy Types

Four decoy configurations are commonly used:

Similar decoy : placed near a competitor with comparable subjective value, forming a “competitor set” that reduces the competitor’s selection probability and indirectly boosts the target.

Compromise decoy : appears worse than the target on dimensions where the target is already strong and better on dimensions where the target is weak, nudging users toward the target.

Attraction decoy : positioned close to the target but with lower overall value, making the target’s advantages more salient.

Phantom decoy : a non‑existent option that is objectively superior to the target, causing users to settle for the target as the next best choice.

Design Practice

Applying the decoy effect involves two steps: find a suitable scenario and set the decoy.

1. Find a Scenario

The effect is most effective in consumption‑related contexts where users make trade‑offs. It is less known among product managers and designers, offering an opportunity for impact.

2. Set the Decoy

In a cloud‑music membership promotion, the original options were “Buy single (2 ¥)” and “Buy membership (5 ¥)”. The team changed the membership option to “Buy membership + single (5 ¥)”. To encourage the target, they added a decoy. After evaluating the four decoy types, they chose an attraction decoy: the original “Buy membership (5 ¥)” served as the decoy, making the new “Buy membership + single” appear more valuable.

The A/B test showed a significant lift in conversion, especially for new users.

Precautions

When using the decoy effect, consider:

Ethics : Ensure the decoy does not harm users or violate social norms.

User age : Young children may not exhibit the effect because they lack the ability to use contextual cues.

Regret emotion : If users feel regret, the decoy’s influence can be weakened.

Time pressure : High time pressure reduces the effect, as users have less capacity to compare options.

Summary

Decoy‑based option design can align user experience with business goals when applied responsibly. Overuse or unethical deployment can damage trust and lead to user churn.